Generic lost and don't know what to do.

Essentially, I have been seeing a wonderful, wonderful girl for the last year and a half.
We both attend the same college and have been dating since freshman year.

We see each other nearly every day as our course work is nearly identical (same majors) and our social circles (clubs, people we know, etc.) are similar.
The catch is that I feel like she's bored.

Up until 2/3 months ago, she was always eager to see me, asked to see me more even.
Now, communication is much more scarce, and while she does talk to me, I feel like it's not as natural as it used to be, and she excuses herself quickly.

I don't know what changed, but I feel like it has to do with the fact that I wasn't there to have fun with her over the last couple of months, that I wasn't entertaining enough. We were both under a very academically tense period and I didn't make enough space to have fun with her.

Here's the thing. I feel like in the past, I've done a lot of acting in our relationship (after the start of the relationship), where I acted more mature and serious than I actually am. As shameful as it is to admit this, I did it because I felt like that was what she would want. This image extended especially more when we were in public, or in our social circles. And it's branded me with the image of the cold, serious, all-work sort of guy with other people. With her, I could be myself much more.

Yes. I've come to realize that may have been a really dumb thing to do, since I wasn't being myself, and being myself probably would have worked a lot better. I just didn't have the faith she would like me as I was, despite her telling me she did. In retrospect, I messed up in this regard.

Now, I've realized that being myself could have made this all work. But she's bored of it all, and I frankly don't know what to do.
The game plan so far is to just ride out break, and come next semester, start hanging out with other, non-mutual friends more often, loosen up and be myself more in social settings with her and our mutual friends, and finally to go on dates more frequently, since we enjoy them when we do go.

But as of right now, I don't know how to deal with the fact that she's bored.
I'm wary of outright talking to her about it. One, because I dislike being the one to bring up problems (I feel like I'm the only one who ever does)
Two, because I could be overanalyzing it all.

Don't bring it up. Stop faking and start being yourself to start. Also, accept that this relationship might be over, and don't beg and try to fix things. Don't be so eager with her. Do your own thing and let her seek you out. There's likely another guy involved too, so you may want to talk to some other girls too.

^^ this. Brilliant advice from BackUp

Thanks for the advice.
What gave you signs there's another guy involved though?

A couple months, she talked about another guy that she had met who was really funny.
She brought him up a lot over a couple weeks. Briefly talked to her about it, asked if there was something going on, and she said not at all.

She's done it since (they see each other occasionally), and every time she sees him, afterwards, she'll make a quick remark about something he said or did.
Bothers me a bit, but I never really brought it up afterwards.

The honeymoon stage of your relationship has come to an end....sometimes people just naturally lose interest ....plus having an interest in someone else will push things along. You are young and in college....this is a time to have different experience and date others.....this is supposed to be the best years, so don't waste your youth on being stuck in a relationship.